1. Technical Field of the Invention
The present invention relates to a mobile telecommunications network and, in particular, to the provision of mobile service to two mobile stations having the same Mobile Subscriber Integrated Service Digital Network (MSISDN) number.
2. Description of Related Art
With conventional wireline telecommunications networks, a number of telephone terminals are often connected to a single telephone line. Consequently, any one of the connected wireline terminals can utilize the associated telephone line to originate outgoing calls and to receive incoming calls over the serving telecommunications network using the associated subscriber data and subscription (e.g., a billing account). These terminals are often referred to as extension phones.
With the introduction of a mobile telecommunications network, such as the Global System for Mobile (GSM) communication and the Personal Communications System (PCS), the concept of wireline telephone service and wireless telephone service has changed drastically. Instead of assigning a telephone number for a particular geographic location or telephone line, in accordance with the GSM or PCS, a telephone number is assigned towards a particular mobile station, or more particularly, the mobile subscriber associated with that mobile station. As a result, each subscriber has a Subscriber Identity Module (SIM) card used for storing necessary mobile subscriber information. The SIM card comprises a detachable memory unit that may be freely associated with any available mobile station. The stored subscriber information includes a mobile subscriber's International Mobile Subscriber Identity (IMSI) number, or other user specified information, such as preferred speed dialing lists or screening lists. By inserting a mobile subscriber's SIM card into a mobile station, the subscriber information stored in the inserted SIM card is available to the mobile subscriber's new terminal. As a result, the mobile subscriber is able to freely utilize any available mobile station while maintaining the same directory number, such as a Mobile Subscriber Integrated Service Digital Network (MSISDN) number, and subscriber feature data.
However, unlike wireline terminals, because each SIM card and its associated mobile station is identified using a unique IMSI number, it is conventionally not possible to assign two different mobile stations or IMSI numbers with the same directory number or MSISDN number. As an illustration, if a mobile subscriber has a vehicle mounted mobile station and a portable handheld mobile station, the mobile subscriber has to subscribe to two different mobile subscriptions and be assigned with two different directory numbers to concurrently utilize both mobile stations. As a result, the mobile subscriber must inconveniently maintain two different subscriber feature data, subscription, and dialable directory numbers for his or her mobile stations. As an alternative, the mobile subscriber may detach the tiny SIM card from one mobile station (e.g., vehicle mounted mobile station) and inserted into the other mobile station (e.g., handheld mobile station) each time the subscriber wishes to switch from one mobile station to the other. However, such a manual switching is rather inconvenient. Furthermore, two mobile subscribers belong to the same household, for example, cannot utilize two different mobile stations at the same time to originate outgoing calls while utilizing the same subscriber data and charging the incurred costs to the same subscription.
Accordingly, there is a need for a mechanism to enable two mobile subscribers and their associated mobile stations to originate and terminate call connections using the same directory number and subscription data.